If you send email to customers it's important that you let them know where the email will come from and then use then use this address consistently. Using different email addresses is a recipe for getting trapped in spam filters. This is equally important for marketing and other messaging like bills and canceled flights.

I bring up flights because I'm flying to the UK later today and was planning to return on Sunday. British Airways' Cabin Crew is going on strike this weekend and my return flight has been canceled. Instead of sending a text message BA tried to notify me by email. This would have been fine if they used the address they've used for years, but instead they used a new address and a new domain. In fact in the process of canceling and re-booking I (eventually) got email from britishairways.com, my.ba.com, email.ba.com and pop3.amadeus.net.

Since I've had the same email address for twelve years now I get a fair amount of spam. I use SpamArrest to keep myself sane:

94.9% of my email is spam. Since I started using the service SpamArrest has eaten 482,494 messages for me. I'm far from alone in using white list based email filtering so if you want your message to get through transparency and consistency are the way to go.